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Fisher 846 Instruction Manual

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Type 846
Type 846 Electro-Pneumatic Transducer
Contents
1. Introduction
Scope of Manual
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This product may be covered by one or more of the following patents (4,481,967; 4,534,376;
4,638,830; 4,653,523; 4,665,938; 4,760,859; 4,777,826; 4,901,756) or under pending patent
applications.
Fisher-Rosemount satisfies all obligations coming from legislation
to harmonise product requirements in the European Union.
Fisher, Fisher-Rosemount, and Managing The Process Better are marks owned by Fisher
Controls International, Inc. or Fisher-Rosemount Systems, Inc.
HART is a mark owned by Rosemount Inc.
All other marks are the property of their respective owners.
Fisher Controls International, Inc. 1994, 1995; All Rights Reserved
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Section 1
Introduction
Scope of Manual
This instruction manual provides installation, operat-
ing, calibration, maintenance, and parts ordering in-
formation for the Type 846 electro-pneumatic trans-
ducer. Refer to separate manuals for instructions
covering equipment used with the transducer.
Instruction Manual
Form 5354
November 1995
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Summary of Contents for Fisher 846

  • Page 1: Table Of Contents

    Fisher-Rosemount satisfies all obligations coming from legislation to harmonise product requirements in the European Union. Fisher, Fisher-Rosemount, and Managing The Process Better are marks owned by Fisher Controls International, Inc. or Fisher-Rosemount Systems, Inc. HART is a mark owned by Rosemount Inc.

  • Page 2: Description

    Specifications The Type 846 is an electronic I/P transducer. It has a Specifications for the Type 846 transducer are listed in single electronic circuit board, as shown in Figure 1-2.
  • Page 3 Type 846 Table 1-1. Specifications Input Signal per SAMA Standard PMC 31.1-1980, Sec. 5.3, Condition 3, Steady State 4 to 20 mA dc, 4 to 12 mA dc, or 12 to 20 Shock Effect: 0.5% of span, when tested per mA dc.
  • Page 4 Type 846 Table 1-1. Specifications (continued) Housing Classification gauges or tire valves, remote pressure read- ing, module cover with multiple stroke ports, CSA Type 4X, NEMA 4X, designed to meet IP66, stainless steel housing, or stainless steel tropicalization (Fungus test per MIL-STD-810)

  • Page 5: Installation

    Type 846 Supply Pressure Section 2 Installation When a control valve is ordered with a Type 846 trans- WARNING ducer specified to be mounted on the actuator, the factory-mounted transducer is connected to the actua- tor with the necessary tubing and calibrated to the Personal injury or property damage may specifications on the order.
  • Page 6 OUTPUT GAUGE PORT 1/4-18 NPT 4.00 TEST PINS (102) O-RING GROOVE FOR FILTER REGULATOR SUPPLY PORT POSITIVE WIRING CONNECTION 1/4-18 NPT NEGATIVE GROUND 5/16-18 (2) NOTE; DIMENSIONS ARE IN INCHES (MILLIMETERS). B2473/IL Figure 2-1. Type 846 Dimensions and Connection Locations 2–2...

  • Page 7: Output Pressure

    OR PILOT STAGE, PREVENTING PROPER TRANSDUCER OPERATION. THE VERTICAL MOUNT IS MOST EFFECTIVE FOR MOISTURE DRAINAGE IN WET APPLICATIONS. 14B7361 A6626–1/IL Figure 2-2. Typical Type 846 Dimensions with Type 67AFR Filter/Regulator and Gauges O-ring gland of the filter-regulator mounting boss. The WARNING filter-regulator contains a 1/4 NPT output port for a supply gauge.
  • Page 8 FOR MOISTURE DRAINAGE IN WET APPLICATIONS. IF MOUNTED ON HORIZONTAL PIPE, THE I/P MUST BE ON TOP OF THE PIPE FOR PROPER MOISTURE DRAINAGE. 14B7332 A6625–1/IL Figure 2-2. Typical Type 846 Dimensions With Type 67AFR Filter/Regulator and Gauges (continued) 2–4...

  • Page 9: Electrical Connections

    (121) B2465/IL INCH (mm) Figure 2–3. Dimensions for Type 846 with CENELEC Certifications Electrical Connections use a conduit drip leg to help reduce liquid buildup in the terminal compartment and avoid shorting of the input signal. Electrical connections are made at the WARNING terminal block.

  • Page 10: Stroke Port

    Before installing Unscrewing the module cover removes the Type 846, ensure the stroke port is clear. Do not power from the electronics and the out- mount the Type 846 in a location where foreign materi- put signal will be 0.0 psig.

  • Page 11: Calibration

    Section 3 Calibration Use the following procedure to achieve a standard 3 to Calibration of the Type 846 requires either an accurate 15 psi (0.2 to 1.0 bar) output span for a 4 to 20 mA current generator or an accurate voltage generator input signal: with a precision 250-ohm, 1/2-watt resistor.

  • Page 12: Multirange Performance: Full Range Input, Direct Action

    15.0 psig (1.0 Excessive current can damage the bar). transducer. Do not connect the Type 846 to an input current of more than 100 mA. 4. Repeat steps 2 and 3 to verify and complete the calibration.

  • Page 13: Standard Performance: Full Range Input, Reverse Action

    Type 846 the span screw to overcorrect the error by a factor of psig (0.03 bar). The output increases with clockwise two. For example, if the reading was 14.95 psig (0.9 rotation of the span screw. bar), adjust the span screw to achieve an output of 4.

  • Page 14: Transporting The Module Final Assembly

    15.0 psig (1.0 bar) in step 4, turn off the air supply. Remove the module final assembly from the housing. After the Type 846 is calibrated in the shop, the mod- Place the range jumper in the L position for Low ule final assembly can be removed from the housing.

  • Page 15: Principle Of Operation

    Figure 4-1. Type 846 Block Diagram This is important when calculating the loop load. When the Type 846 is used in series with a microprocessor- based transmitter, the noninductive nature of the Type 846 allows digital signals to successfully pass through Section 4 undistorted.

  • Page 16: Booster Stage

    Type 846 HIGH OUTPUT PRESSURE REGULATED AIR SUPPLY PRESSURE TO BOOSTER STAGE DEFLECTED NOZZLE FLOW PATTERN PRESSURE TO REGULATED BOOSTER STAGE AIR SUPPLY A6645/IL Figure 4-3. Deflector/Nozzle Pilot Stage Operation (Direct Action) a linear relationship between the coil current and the Booster Stage pilot stage output pressure.

  • Page 17: Troubleshooting

    If a control loop does not perform properly and the cause of malfunction has not been determined, two features of the Type 846 can be used to determine if the transducer is at fault: the stroke port and Remote Pressure Reading.

  • Page 18: In-Service Troubleshooting

    A number of simple checks can be made on the Type transducer before attempting to remove 846 while the unit is in service. Figure 5–5 shows a the terminal compartment cover or mod- troubleshooting flowchart.
  • Page 19 8.5 volts indicates a problem with 8. Remove the terminal compartment cover (see the Type 846, a faulty or corroded connection at the Warning above), and short the loop across the positive transducer, or an overcurrent condition. Replace the (+) and the negative (–) terminals to check the output.

  • Page 20: Troubleshooting In The Shop

    10. Prepare to remove the module final assembly 4. Remove the module from the module cover and from the housing, or to remove the Type 846 from its inspect the pilot/actuator assembly for damage or mounting bracket. Refer to Module Final Assembly clogging.
  • Page 21 Reassemble and check operation. b. Make sure the O-rings are lightly lubricated with silicone grease and properly seated. d. If the Type 846 does not function, replace the electronic circuit board with a new one. Refer to c. Reassemble and check operation.
  • Page 22 Type 846 5–6...

  • Page 23: Maintenance

    The active mechanical and electrical components of matically disengage. The internal air ports are also the Type 846 are incorporated into a single, field–re- disengaged. The air supply to the transducer should placeable module called the module final assembly, as be turned off to prevent uncontrolled air loss through shown in Figure 6-1.
  • Page 24 ASSEMBLY SCREWS MODULE FINAL ASSEMBLY SCREWS V-GROOVE MODULE FEET SLIP RING O-RING MODULE COVER INDICATING BOSS KEY SLOT STROKE PORT SCREEN ALIGNMENT KEY RETAINING CLIP (2) O-RING CLIP COVER SLOT (2) MODULE COVER C0790/IL Figure 6-1. Type 846 Exploded View 6–2...

  • Page 25: Replacing The Module Final Assembly

    WARNING CAUTION Explosions may cause death or serious injury. Do not operate the Type 846 with Do not grip the module cover threads. the CENELEC flameproof options at a The threads are sharp and may cause supply pressure in excess of 20 psi (1.4 minor injury.

  • Page 26: Electronic Circuit Board

    Electronic Circuit Board 7. Prepare to insert the module into the housing. Align The Type 846 electronic circuit board is located on top the V-groove located on the module final assembly of the module final assembly, as shown in Figure 6-1.

  • Page 27: Range Jumper

    D position, the RPR feature does not operate. When the RPR feature is included, the Type ELECTRONIC CIRCUIT 846 is shipped with the RPR jumper in the N position. BOARD MANIFOLD For more information about the RPR feature, refer to Remote Pressure Reading (RPR) in Section 5.

  • Page 28: Pilot/Actuator Assembly

    Type 846 DEFLECTOR BAR ALIGNMENT WIRE WIRE RUBBER DIAPHRAGM PLASTIC HOUSING A6655/IL MOUNTING Figure 6-8. Cleaning the Nozzles SCREWS or nozzles. Doing so could alter the alignment or disable the deflector/ nozzle mechanism. A6654/IL The assembly can be inspected for a buildup of for- eign material.

  • Page 29: Module Subassembly

    (–) terminal. vironment from the Type 846. The exhaust port screen The test points allow the input current to be deter- is located behind the nameplate. Removing the two...
  • Page 30 Type 846 6–8...

  • Page 31: Parts List

    Type 846 Section 7 Parts List Whenever corresponding with the Fisher sales office replacement parts, refer to the 11-character Fisher or sales representative about this equipment, always part number of each required part. Figure 7-1 shows mention the transducer serial number. When ordering the key numbers for all replaceable parts.
  • Page 32 Type 846 B2467/IL Figure 7-1. Type 846 Exploded Parts Drawing 7–2...
  • Page 33 Type 846 B2468 / IL Figure 7-1. Type 846 Exploded Parts Drawing (continued) 7–3...
  • Page 34 Type 846 Output and Supply Gauges Output Gauge Supply Gauge Range Range Brass Brass Triple Scale 0-30 psi/0-0.2 MPa/0-2 bar 11B8579 X022 11B9639 X012 11B8580 X062 11B9639 X012 0-60 psi/0-0.4 MPa/ 0-4 bar 11B8579 X032 11B9639 X022 11B8580 X022 11B9639 X022...

  • Page 35: Loop Schematics

    Type 846 Section 8 Loop Schematics This section includes loop schematics required for wir- ing of intrinsically safe installations. If you have any questions, contact your Fisher Controls sales repre- sentative or sales office. CSA Schematics 13B8779-A/ doc 8–1...
  • Page 36 Type 846 FM Schematics 13B8780-A/ doc For information, contact Fisher Controls: Marshalltown, Iowa 50158 USA Cernay 68700 France Sao Paulo 05424 Brazil Singapore 0512 8–2 Printed in U.S.A.

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